Although the Big Wheel and the Green Machine were both front wheel drive, it was the latter's rear wheel that turned  much like a forklift. Being physically longer, the Green Machine had a larger turning radius than the Big Wheel  this may explain their lack of use as Zambonis at ice rinks  making it more difficult (than with a Big Wheel) to do spin-outs.

The Green Machine was also steered differently; the rear wheel was turned by the means of two levers a'la BattleZone. This "different" control mechanism may have limited the number of it's sales  indeed I only knew one or two kids with them.

A computer or peripheral device that has
been designed and built to military specifications for field
equipment (that is, to withstand mechanical shock, extremes of
temperature and humidity, and so forth). Comes from the olive-drab
`uniform' paint used for military equipment.